Submission #1177960

#	Time	Username	Problem	Language	Result	Execution time	Memory
1177960		batman3747	Detecting Molecules (IOI16_molecules)	C++20	Compilation error	0 ms	0 KiB

molecules

#include "bits/stdc++.h"
#define all(x) (x).begin(), (x).end()
#define debug(x) cerr << (#x) << " " << (x) << endl
#define SZ(s) ((int)s.size())
#define pb push_back
#define ff first
#define ss second
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;

int* find_subset(int s, int e, int* w){
  int n = sizeof(w);
  map<int, vi> mp;
  for(int i = 0; i < n; i ++){
    mp[w[i]].pb(i);
  }
  sort(w, w + n);
  vi pref(n + 1);
  for(int i = 1; i <= n; i ++) pref[i] = pref[i - 1] + w[i - 1];
  int l = 1, r = n;
  vi ans;
  while(l <= r){
    int m = (l + r) / 2;
    int s1 = pref[m] - pref[l - 1], s2 = pref[r] - pref[m];
    if(s1 >= s && s1 <= e){
      for(int i = l - 1; i < m; i ++){
        ans.pb(mp[w[i]].back());
        mp[w[i]].pop_back();
      }
      break;
    }
    if(s2 >= s && s2 <= e){
      for(int i = m; i < r; i ++){
        ans.pb(mp[w[i]].back());
        mp[w[i]].pop_back();
      }
      break;
    }
    if(s1 < s) l = m + 1;
    else if(s2 > e) r = m - 1;
  }
  sort(all(ans));
  int m = SZ(ans);
  int res[m];
  for(int i = 0; i < m; i ++) res[i] = ans[i] + 1;
  return res;
}

int main(){
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  return 0;  
}

Compilation message (stderr)

molecules.cpp: In function 'int* find_subset(int, int, int*)':
molecules.cpp:48:10: warning: address of local variable 'res' returned [-Wreturn-local-addr]
   48 |   return res;
      |          ^~~
molecules.cpp:46:7: note: declared here
   46 |   int res[m];
      |       ^~~
molecules.h:1:9: warning: #pragma once in main file
    1 | #pragma once
      |         ^~~~
molecules_c.h:1:9: warning: #pragma once in main file
    1 | #pragma once
      |         ^~~~
/usr/bin/ld: /tmp/ccOcF4oT.o: in function `main':
grader.cpp:(.text.startup+0x0): multiple definition of `main'; /tmp/ccvygYoM.o:molecules.cpp:(.text.startup+0x0): first defined here
/usr/bin/ld: /tmp/ccOcF4oT.o: in function `main':
grader.cpp:(.text.startup+0x173): undefined reference to `find_subset(int, int, std::vector<int, std::allocator<int> >)'
collect2: error: ld returned 1 exit status